Post Exertional Malaise
What it is:
Post-exertional malaise commonly known as PEM is an exacerbation of all symptoms of MECFS 24-48 hours after physical or mental exertion. These symptoms include but are not limited to
-Fever
-Sore throat
-Runny nose
-Headache
-Joint pain
-Muscle pain
-Muscle spasm
-Muscle weakness
-Brain fog/confusion
-Slurred speech
-Air hunger (a feeling of not being able to breathe effectively)
-Gastroparesis
-Dysautonomia
-Tachycardia
-Temperature imbalance
-Orthostatic Intolerance
-Paralysis
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What causes PEM?
While we do not know the exact cause 2-day Cardiopulmonary Excercise Testing by the Workwell Foundation has revealed significant decreases in metabolic functioning and ability to process and utilize oxygen during PEM. The anaerobic threshold or the point at which the body shifts from sustainable aerobic exercise using oxygen to unsustainable anaerobic exercise building up lactic acid is decreased. We also know from perfusion studies that significantly less oxygen reaches the brain while in PEM.
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How do I avoid PEM?
PEM can be avoided in most patients by cutting back their activity and exertion to below their "limit" the point at which they trigger PEM. Finding your personal limit can be challenging. A common recommendation is starting with half of what you feel you could physically do. However, in severe or very severe patients essential activities like eating and hygiene may trigger PEM unavoidably. See my post "Pacing is different for ME" for more guidance.
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I can't identify distinct episodes of PEM but I think I have ME... what should I do?
Many people who have just been diagnosed with ME will be in "rolling PEM." This means they are doing too much every day and experiencing PEM every day as well. These people should try resting completely for a week and observe whether their symptoms decline. If they do they should slowly build up activity until they find their limit then stay under that limit going forward.
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I am crashing immediately after activity, not 24-48 hours later... is this PEM?
If you overexert an extreme amount (most common in new patients) it is possible to suffer muscle cramps, spasms, paralysis, dizziness, headache, and other symptoms immediately following exertion. While this is not exactly PEM it is common in ME patients and a sign that you have done far too much and you will likely also experience PEM after this immediate reaction. It can sometimes be easier to notice these sorts of crashes than PEM especially if you are in rolling PEM.
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I experience ______ 24-48 hours after exertion but it's not a listed symptom of PEM. Is this part of ME / PEM?
In general people with ME should still have any new symptoms checked out to rule out other conditions or comorbidities. However, while you should still check with your doctor, if your symptom happens consistently after overexertion during the 24-48 hour window it is most likely PEM. There is not an exact guide to what symptoms constitute PEM, as PEM is defined by the reaction to exertion, not specific symptoms.
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What is the difference between a flare, relapse, crash, and PEM?
A flare is generally used to refer to a temporary exacerbation of symptoms in any autoimmune or autoinflammatory disease. PEM could be considered a special type of flare. A relapse is a long-term decline in baseline (your day-to-day level of functioning). PEM is not a relapse, but it can cause one, especially if you continue to exert when in PEM. A crash is a general term for an exacerbation of symptoms following a trigger like stress or exertion. People with other diseases to ME can have a crash following a big day, even if they do not have the specific energy deficiencies seen in PEM. PEM is a specific type of crash.
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What is the difference between PEM, PENE, and PESE?
These are all just different names for the same process. PENE stands for Post Exertional Neuroimmune Exhaustion and PESE stands for Post Exertional Symptom Exhasurbation.
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Do other diseases have PEM?
This is controversial as some diseases like EDS have a high prevalence of PEM in the patient population. However, many people with these diseases also carry a diagnosis of MECFS. So either you could say that ME is commonly comorbid with these diseases or that these diseases also feature PEM. However, ME is the only disease for which PEM is a required diagnostic feature.
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Why do we have PEM?
As previously stated the exact cause of PEM is unknown. However, the symptoms of PEM seem to serve an important function in the body of ME patients as it is essentially a way of saving energy during energy deficiencies. Paralysis, extreme exhaustion, pain, light sensitivity, all of these symptoms keep patients in bed and unable to expend large amounts of energy at a time when the body's energy systems are failing. So while PEM can be incredibly frustrating and feel like a punishment, it is quite possible that without PEM, ME would be a much more deadly disease.
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So hopefully you now have a better understanding of PEM. What do you wish your friends and family knew about PEM? What symptoms of PEM do you find most difficult?
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Myalgic Encephalomyelitis is a disease defined not by inability but by consequences. Post-exertional Malaise or PEM is the consequence.
As a follow-up to "Pacing is different for MECFS" here is a post elaborating on why: PENE, PESE, PEM, all names for the terrible consequences we face as a reaction to overexertion. Oftentimes, overexertion is as mild as simply talking too long or taking a shower.
My personal symptoms of PEM include:
Sore throat
Nausea
Headache/migraine
Increased light and noise sensitivity
Joint pain
Brain fog
Extreme fatigue
Muscle spasms
Muscle cramps
Paralysis episodes
Other common symptoms of PEM include:
Dizziness
Orthostatic intolerance
Temperature intollerance
Gastroparesis
Slurred speech
Air hunger
Fever
Runny nose
However, there is no exact list of symptoms of PEM, it is only defined as an exacerbation of symptoms 24-48 hours after exertion.
Because PEM can often not occur until 1 or 2 days after the triggering incident, persons with ME and severe ME patients in hospital are often not listened to when they try to explain that they need something (a rest, a quiet room, darkness, etc) to avoid PEM. Friends and family members rarely see us on days we are in PEM leading to misunderstanding of how sick we are and how much we sacrifice to see them.
If you experience PEM and are not diagnosed with MECFS I highly recommend checking out the ICC diagnostic criteria for MECFS. PEM is the defining symptom of ME and catching it early can help you to better deal with the illness and avoid becoming severe.
